Gas turbine engines



Jan. 21, 1964 J. G. KEENAN ETAL 3,118,275

GAS TURBINE ENGINES Filed March 5, 1962 4 Sheets-Sheet lL s4 w www( 252124 @31920 Jan- 21, 1964. J. G. KEENAN ETAL 3,118,276

GAS TURBINE ENGINES 4 Sheets-Sheet 2 Filed March 5, 1962 `Ian. 21, 1964 Filed March 5, 19

J. G. KEENAN ETAL 3,118,276

GAS TURBINE ENGINES 62 4 Sheets-Sheet 3 Jan. 21, 1964 J, G. KEENAN ETAL 3,118,276

GAS TURBINE ENGINES Filed March 5, 1962 4 Sheets-Sheet 4 /17 OAWE YS Unted States Patent O 3,118,276 GAS TURBiNE ENGINES John G. Keenan, Derby, .lack Palfreyman, Tansley, near Matlock, .lohn Bertram Hoiliday and David John Pickerell, Derby, England, assignors to RoHS-Royce Limiterl, Derby, Engiand Filed Mar. 5, 1962, Ser. No. 177,360 Claims priority, appiication Great Britain M 21, 1961 14 Claims. (Cl. 6i-35.6)

This invention relates to gas turbine engines and is more particularly concerned with engines of the type hereinafter referred :to as by-pass or ducted fan engines.

A by-pass engine is one which comprises a compressor system having a low pressure compressor section from which air is delivered partly to a high pressure compressor section and partly to a iiow passage which by-passesv the high pressure compressor section, combustion equipment receiving air compressed in the high pressure compressor ection and =a turbine system which receives the products of combustion from said combustion equipment, and in which the by-passed air flowing in said passage and the exhaust gases from said turbine system are passed to atmosphere through propelling nozzle means to provide propulsive thrust.

A ducted fan engine is one which includes one or more fan rotors which are driven by the rotor system of the engine and which cause air to flow through a duct surrounding the engine.

In engines used for aircraft propulsion, it is known to burn `additional fuel in the exhaust gas passing from the turbine lto atmosphere in order to augment the propulsive thrust of the engine, and the present invention is concerned with by-pass or ducted fan engines having additional combustion equipment for this purpose.

According to the present invention there is provided a gas turbine by-pass or ducted fan engine in which the duct, through which flows the by-pass or fan air, communicates with the exhaust gas duct downstream of the [turbine or turbines through one or more mixer chutes which extend into the exhaust gas duct, each chute being provided with valve means which in one position close off the inlet to each chute and allow the by-pass or fan air to flow through the portion of the duct downstream of the chutes `and in another position allows by-pass or fan air to pass into each chute so as to be mixed with the hot exhaust gases and prevents a ilow through the duet downstream of the chutes, means also being provided for injecting fuel into the hot exhaust gases upstream of said chutes so that the chutes act as flame stabilising means for the reheat combustion.

Preferably the valve means prevent a iiow of air through said ychutes into the exhaust gas `duct when reheat fuel is being injected into the exhaust gases.

During the period of reheat combustion the air in said duct may be mixed with the exhaust gases downstream of said chutes, preferably downstream of the reheat combustion zone.

Alternatively, the `air in said duct may pass to atmosphere through Va fixed outlet nozzle at the downstream end of said duct during reheat.

In a preferred arrangement the reheat fuel may be injected into the hot exhaust gases through fuel injection nozzles located in struts which support the exhaust cone of the engine from the outer casing.

The engine may be provided with means for deecting the exhaust gases to atmosphere in a forward direction so las to produce a reverse component of thrust on the aircraft in which lthe engine is mounted.

Where gas deflecting means are provided said means are preferably located immediately downstream of said chutes, said duct extending around the means.

3l @,275 Patented Jan. 21,V 1954 ICC In one arrangement the valve means associated with each chute comprises a pivoted ilap valve which is contained within a box-like chamber formed by side walls which extend between the inner and outer walls of the said duct, said side walls of each chamber converging towards each other in la downstream direction, the lower wall of said Chamber being in communication with said chute.

Each ilap valve is moved by one or more piston and cylinder ydevices located between adjacent radi-a1 walls of adjacent box-like chambers.

In another arrangement the valve means associated with each chute comprises an arcuate pivoted flap valve which extends circumferentially of the duct, through which flows the by-pass or fan air, the adjacent edges of adjacent flap valves being in overlapping relationship.

Preferably each ap valve is .provided with a roller or rollers on its upper surface, said roller engaging with an inclined surface carried by or formed on an axially movable ring which encircles said flap valves.

The roller or rollers are preferably supported in bearings carried by radially extending ribs provided on the upper surface of each flap valve.

The axially movable ring is preferably caused to be moved axially of lthe engine by a number of piston and cylinder devices located in said duct downstream of the pivots of said ap valves.

Some or each of said mixer chutes may be provided with means for igniting the fuel supplied fro-m the reheat fuel injection means. Preferably said ignition means comprises a catalytic igniter.

By lusing the chutes as stabilising means for the reheat combustion and injecting the reheat fuel through nozzles loc ted in the struts supporting the exhaust cone full use is mad-e of existing parts and there is no need to include extra reheat equipment, 'thereby giving Ia saving in weight, and also substantially eliminating the pressure losses normally associated with `reheat equipment when inoperative.

Where means are provided for deflecting ,the exhaust gases to atmosphere in a forward direction, the means may be located close to the mixer chutes thereby giving a considerable saving in length as compared with an engine in which reheat stabilising means 4are provided in addition to the mixer chutes.

By passing the whole of the by-pass or fan air through the chutes the gas deecting means lis able to deflect the whole of the exhaust gases 'and by-pass yor fan air and is designed to suit the diameter of the exhaust duct. Also, as the air in the by-pass duct is not directed into the chutes during reheat operation the diameter of the exhaust pipe in this region can be smaller than if the whole of the by-pass air and exhaust gases are reheated and this diameter can be designed more easily to give the required Mach number for the reheat gases.

Two embodiments of the present invention will now be described with reference to FIGURES l to 7 of the drawings which accompanied the specication and in which:

FIGURE 1 is a diagrammatic section through a bypass gas turbine engine embodying the present invention,

FIGURE 2 is an enlarged View of part of the engine shown in FIGURE l illustrating one embodiment of the present invention.

FIGURE 3 is a section taken on the line 3-3 indicated on FIGURE 2. y

FIGURE 4 is a view taken in the direction of the arrow 4 indicated on FIGURE 3 with part of the outer wall broken away to show details.

FIGURE 5 is a view similar to that of FIGURE 2 showing another embodiment of the present invention.

FIGURE 6 is a View taken in the direction of the ararrears 3 row 6 indicated on FIGURE 5 with parts broken away to show details, and

FIGURE 7 is a section taken on the lline 7-7 indicated on FIGURE with the operating mechanism omitted.

The gas turbine engine shown in FIGURE l comprises a low pressure compressor 10 which receives air from a forwardly facing air intake 11, a high pressure cornpressor 12 which receives a proportion of the air compressed in the low pressure compressor 10 and delivers to combustion equipment 13 where fuel is burned in the air, the products of combustion passing through a high pressure turbine 14 which drives the high pressure compressor 12 through shafting 15 and a low pressure turbine 16 which drives the low pressure compressor 10 through shafting I17. After driving the turbines 14, 16 the hot gases exhaust into a jet pipe 18 and are then exhausted to atmosphere through Ia variable propelling nozzle 19.

The low pressure compressor 12 also supplies compressed air to a by-pass duct 20* which by-passes the air around the high pressure compressor 12, combustion equipment 13 and turbines 14 and 16. Located downstream of the low pressure turbine 16 are a number of mixer chutes 21 which extend radially into the path of the hot gases passing into the jet pipe 18. Downstream of the mixer chutes y21 is a jet deflector unit 22 which comprises two movable va'lve members 23` which are movable from the position shown in which they prevent a gas flow into curved vanes 24 and allow the exhaust gases to flow to the propulsion nozzle 19, to a position in which they prevent a flow of exhaust gas to the nozzle 19 and allow the gases to pass through the vanes 24 and be directed to atmosphere in a forwardly direction so as to produce a breaking effect on the aircraft in which the engine is mounted.

The mixer chutes 21 are shown more clearly in FIG- URES 2 to 4 and it will be seen that each chute 21 is provided with a movable valve member 25 which is pivoted at its downstream end to the jet pipe 18 and extends between a pair of side walls 26a and 2Gb. The side walls 26a, 26h extend from between the inner wall 18a and the outer wall 20a of the by-pass duct 20 forming a box-like structure.

The side walls 26a, `26b associated with each mixer chute .21 converge towards each other in a downstream di-rection so forming spaces or pockets 27. Each valve member 25 is caused to be moved by a linkage 28 which is moved by a piston and cylinder device 29.

Upstream of the mixer chutes 21 is an exhaust cone 30 which is supported from the inner wall 18a of the by-pass duct 20 by a number of radial struts 31. Each strut 31 is provided with a fuel delivery pipe `'32 having outlet nozzles 33 formed in the trailing edge of the struts 31.

During normal operation of the engine the valve members 25 are in the position shown in which the whole of the by-pass air flow is mixed with the hot propulsive gases before being exhausted to atmosphere through the propulsion nozzle *19.

If, during landing of the aircraft, it is necessary to produce a braking effect on the aircraft the valve members 23y are moved to the reverse thrust position and the whole of the hot gases and by-pass air are detiected through the curved vanes 24.

If, for example during take-off, it is necessary to provide yadditional thrust from the engine, reheat fuel is supplied to the fuel delivery pipes 32 and injected into the hot exhaust gases through the nozzles 313. The valve members 25 are moved by the piston and cylinder devices 29 to the position in which theyl prevent a ow of by-pass air into the interior of the mixer chutes 21 and allow the by-pass air -to flow into the downstream end of the by-pass duct 20 where the by-pass air then ows into the jet pipe 18 through apertures 34 to mix with the reheated exhaust gases.

By injecting the reheat fuel into the exhaust gases upstream of the mixing chutes 21, the stagnant zone immediately downstream of each chute 21 provides stable combustion zones for the burning of the reheat fuel.

It will be appreciated that by using the chutes 21 as flame stabilisers and injecting the reheat fuel through the struts 31 no further reheat equipment is necessary and this also allows the jet deector means 22 to be located [further upstream than would be possible with additional reheat equipment.

Also by allowing the by-pass air to flow into the downstream end of the by-pass duct before mixing it with the exhaust gases the diameter of the jet pipe 18 can be smaller than would be necessary if the whole of the bypass air and exhaust gases were reheated. The diameter of the jet pipe 1S can then be chosen to be more suitable to the Mach number of the exhaust gases.

Instead of providing a variable nozzle such as the nozzle 19 and instead of providing outlets 34 it may be more desirable to provide the downstream end of the by-pass duct 20 with a rearwardly facing fixed outlet nozzle and to provide a xed outlet nozzle for the jet pipe 18. In such an arrangement the effective area of the xed out-let nozzle of the jet pipe 18 would be such as to suit normal engine operating conditions, that is when by-pass air and exhaust gases are mixed in the jet pipe 18. The effective arearof the fixed outlet nozzle at the end of the by-pass duct 26 -would be such as to suit the engine conditions during reheat, and the degree of reheat would be chosen to suit the fixed nozzle of the jet pipe 18.

The advantage of of such an arrangement is that there would be a saving in weight by having no variable nozzle.

In the embodiment shown in FIGURES' 5 to 7 the bypass duct 50 is formed by an outer wall 51 and -an inner wall 52. Mixer chutes 53y extend radially into the exhaust gas duct 54 and are secured -to the inner wall 52 of the by-pass duct 50. Each mixer chute 53 has associated with it an arcuate flap valve 55 which is provided on its upper surface with six radially extending ribs 56. The four ribs 56 which are located in the mid-span region of each iiap valve 55 extend beyond the downstream edge of each apvalve 55 and attached to each of the four mid-span ribs 56 are bearing cages 57 which support the ends of pivot pins 58 each of which extend between two of the ribs 56. The pivot pins 58 extend through bores provided in a pivot mounting 59' which is secured to an axially extending ring 60 surrounding and carried by the inner wall 52.

Encircling the flap valves 55 is a truste-conical ring 61 provided on its inner surface with a number of inwardly radially extending cam plates 62. There is a cam plate 62 associated with each iiap valve 55 and each is provided with an inclined slot 63 forming a cam track. Two ribs Se of each iiap valve 55 carry bearings 64 in which are supported the ends of a pin or roller 65 which engages with the inclined slot 63.

The frusto-conical ring 1 is caused to be moved axially within the by-pass duct 5t? by having its downstream end connected to the piston rods 66 of a number of piston andcylinder devices 67. The cylinder of each device 67 1s prvoted at 68 to a radially extending web 69. Compressed air is supplied to the cylinder of each device 67 by means of conduits 7G.

In the position shown in full lines in FIGURE 5 the upstream edge of each ap valve 55 is caused to seat on a sealing ring 71. As will be seen more clearly in FIGURE 7 the adjacent edges of each pair of flap valves 55 are arranged in overlapping relationship.

In operation or the engine when it is desired to move each ap valve 55 from the position in which the inlets to the mixer chutes 53 are open to the interior of the bypass duct Sii to a position in which they are closed, the piston and cyiinder devices 67 move the frusto-conical ring 61 to the left, as viewed in the drawings, and the inclined siots 63 act on the rollers 65 causing the iiap valves 55 to move about the pivot pins SS to tbe closed position.

Upstream of tlre mixer utes 53 are a number of struts 72 w'nicn support tbe ex aust cone .73 from the inner wall SZ. Surrounding each strut 72 is a sheet metal fairing 74 of aerofoil shape in cross-section. The downstream edge of each iairing 7s is provided with a fuel injector 75 whicb` is supplied with fuel from a conduit Wben it is desired to rebeat tb exliaust gases in order to obtain extra boost, the lap valves 55 are moved to tbe position in which they close ofi tlie inlet to eacli mixer cbute 53 and rebeat fuel is injected into the bot oropulsive stream from tbe fuel iv ectors 75. The fuel/gas mixture is ignited in the region of tbe downstream end oi the mixer chutes 53 by catalytic igniters w'nicb are indicated at '77.

lownstream i the r ixer chutes 53 is a tl rust reverser uint 73 similar to the one described with reference to FGURES 1 to 4.

instead of pivoting eacn piston cylinder device e7 at its downstream end to the we 59 it may be mounted in trunnions extending on eacn side of it as shown at 79. ln suoli arrangement tbe air for operating tbe device 67 may be supplied through the trunnions 79 thus allowthe thrust reverser unit 72; to be mounted closer to tire mixer chutes :'53 as shown at S9. This would reduce engine length and give an increased saving weight.

What we claim is:

1. in a bypass gas Iturbine jet reaction engine having an engine casing housing compressor means, combustion equipment, turbine means arranged in series and a jet pipe for tire llow of turbine exhaust gases, the improvement comprising: a lay-pass duct having its upstream end cornrnunicating with tbe compressor means for receiving a portion of air compressed tberebv, said bypass duct extending past the combustion equipment and turbine means and terminating adjacent the downstream end of said jet oil e; a plurality of mixer cnutes eacb having an upstream end communicating witlr tbe by-pass duct and a downstream end extending into tire jet pipe downstrea n of the turbine means; rebeat fuel injection rneans extending into the iiow of turbine exnaust gase upstream of said mixer chutes and immediately downstream or said turbine means; valve means adjacent tbe upstream end of each of said chutes and selectively operable to a rst position for allowing by-pass air to dow LArough said bypass duct and be discharged from tbe downstream end thereof adjacent the downstream end of said jet pipe to a second Jposition Jfor allowing oy-pass air to pass 'Lito said chutes and be mixed with turbine exhaust gases while preventing iiow through said lay-pass duct to the downstream end thereof, said mixer chutes being positioned in said jet oipe to act as stabilizing means for relieat combustion when said valve means is in said first position.

2. A by-,oass gas turbine jet reaction engine as claimed in claim 1 including a xed outlet nozzle at the downstream end of said jet pipe and including a rearwardly facing xed outlet nozzle on tire downstream end of said by-pass duct adjacent the outlet nozzle of said jet pipe.

3. A by-pass gas turbine jet reaction engine as claimed in claim 1 in which the downstream end or said oy-pass duct includes apertures communicating with the interior of the jet pipe adjacent its downstream end through which by-pass air can mix with turbine exnaust gases clownstream of the rebeat combustion zone.

4. A by-pas gas turbine jct reaction engine as claimed in claim l including an exhaust cone immediately downstream ot said turbine means, a plurality or" struts extendmaeva d ing inwardly from tlie engine casing and supp exhaust cone, said struts housing s n means.

5. A by-pass gas turbine reac le as claimed in claim 4 in which said struts housing said relieat fuel iniection means ar in long .adinal alignment witli mixer chutes.

6. A by-pass gas turbine iet retion engine as cl 'med in claim 1 including tbrust reverser means posicned downstream of said mixer clutes for turbine erhaust gases to atmosphere 1n a substant' ,f forward drrecion.

7. A by-pass gas turbine jet reaction engine as claimed in claim l including a pair of side walls extending along tbe inlet opening of eacb mixer chute a downstream direction, said side walls extending between tbe inner and outer Walls of said byfoss duct and converging in a downstream direction to dene tire box-like chamber, and Wberein said valve means include a pivoted lian valve contained witnin eacb box-like chamber between its respective side walls.

8. A bjr-pass gas turbine giet reaction engine as claimed in claim 7 including piston and cylinder devices positioned in said by-pass duct between side walls of adjacent box-like chambers, said piston cflinder devices being operatively connected to said valves for selectively moving tbe same between tbe inst position and tbe second position.

9. A by-,t ass gas turbine jet reaction engine as clauned in clair i 1 in which tbe valve means associated with each cbute comprises an arcuate pivoted flap valve extending circurnierentially of said by-pass duct, said arcuate pivot flap valve having its edges overlapping the adjacent arcuate pivot ilap valve.

10. A by-pass gas turbine jet reaction engine as claimed in claim 9 including a roller carried on tbe upper surface of each nap valve, an axially movable ring positioned in said by-pass duct and encircling said flap valves, said ring having an inclined surface for engaging said roller and pivoting tire llap valve when tire ring is moved axially.

11. A by-pass gas turbine jet reaction engine as claimed in claim l() including radially extending ribs provided on the outer surface on eaclr of said lap valves, bearing means carried by said ribs, said bearing means supporting said roller.

l2. A by-pass turbine jet reaction engine as claimed in claim 10 in which said inclined surface on said ring includes a radially inwardly extending cam plate having a slot therein for receiving said roller.

13. A by-pass gas turbine jet reaction engine as claimed in claim 10 including means to axially move said ring, said means including a plurality of piston and cylinder devices positioned in said by-pass duct downstream of the pivots of said llap valves.

14. A 1tay-pass gas turbine jet reaction engine as claimed in claim 1 including means for fuel supplied from said rela-eat fuel injector means, said means comprising a catalytic igniter.

ofting said References Cited in tne tile of this patent UNITED STATES l ATENTS 

1. IN A BY-PASS GAS TURBINE JET REACTION ENGINE HAVING AN ENGINE CASING HOUSING COMPRESSOR MEANS, COMBUSTION EQUIPMENT, TURBINE MEANS ARRANGED IN SERIES AND A JET PIPE FOR THE FLOW OF TURBINE EXHAUST GASES, THE IMPROVEMENT COMPRISING: A BY-PASS DUCT HAVING ITS UPSTREAM END COMMUNICATING WITH THE COMPRESSOR MEANS FOR RECEIVING A PORTION OF AIR COMPRESSED THEREBY, SAID BY-PASS DUCT EXTENDING PAST THE COMBUSTION EQUIPMENT AND TURBINE MEANS AND TERMINATING ADJACENT THE DOWNSTREAM END OF SAID JET PIPE; A PLURALITY OF MIXER CHUTES EACH HAVING AN UPSTREAM END COMMUNICATING WITH THE BY-PASS DUCT AND A DOWNSTREAM END EXTENDING INTO THE JET PIPE DOWNSTREAM OF THE TURBINE MEANS; REHEAT FUEL INJECTION MEANS EXTENDING INTO THE FLOW OF TURBINE EXHAUST GASES UPSTREAM OF SAID MIXER CHUTES AND IMMEDIATELY DOWNSTREAM OF SAID EACH OF SAID CHUTES AND SELECTIVELY OPERABLE TO A FIRST POSITION FOR ALLOWING BY-PASS AIR TO FLOW THROUGH SAID BYPASS DUCT AND BE DISCHARGED FROM THE DOWNSTREAM END THEREOF ADJACENT THE DOWNSTREAM END OF SAID JET PIPE AND TO A SECOND POSITION FOR ALLOWING BY-PASS AIR TO PASS INTO SAID CHUTES AND BE MIXED WITH TURBINE EXHAUST GASES WHILE PREVENTING FLOW THROUGH SAID BY-PASS DUCT TO THE DOWNSTREAM END THEREOF, SAID MIXER CHUTES BEING POSITIONED IN SAID JET PIPE TO ACT AS FLAME STABILIZING MEANS FOR REHEAT COMBUSTION WHEN SAID VALVE MEANS IS IN SAID FIRST POSITION. 